A. Field of the Invention
The present invention relates generally to bearings for supporting a load for axial and rotational motion relative to a shaft, and more particularly to a bearing having a plurality of bearing pads designed to exert a static preload on the shaft to achieve a zero clearance fit between the shaft and bearing pads.
B. Description of the Prior Art
It is known in the prior art to provide bearings with circumferentially spaced bearing pads connected to an outer cylindrical shell which are designed to deflect and change shape under loading. For example, Patent Nos. 5,112,143 and 5,284,392 to Ide teach hydrodynamic bearing embodiments having bearing pads structured to move in any direction under loading to optimize formation of a converging hydrodynamic wedge, equalize loading on the bearing pads, and correct for any shaft misalignment. However, the bearing embodiments of Ide are generally concerned with problems associated with high rpm rotational shaft motion, and do not address problems associated with high precision linear (axial) motion.
Linear ball bearings specifically designed for high precision axial motion, such as those manufactured by Thomson Industries, Inc., are expensive. Less expensive standard sleeve bearings require a lapping operation with the shaft in order to achieve a "zero clearance fit" necessary for precision motion.